(1) Field of the Invention
The present invention pertains to an instrument for subcutaneously, intramuscularly, or intraperitoneally injecting implants through animal hide wherein the instrument is comprised of a tubular injector body and a push rod dimensioned to be inserted longitudinally through an interior bore of the injector body. The injector body is formed with a pair of laterally spaced tines at one end with one of the tines projecting longitudinally beyond the second of the tines and presenting an incising tip that facilitates piercing the hide prior to insertion of the tines beneath the hide.
(2) Description of the Related Art
Prior art methods of inserting implants or substances into animals subcutaneously, intermuscularly, or interperitoneally typically require that an incision be made that permits the implant to be injected through the incision. Use of a tubular trocar or a large needle would at times result in a core of flesh or hide of the animal being formed in the piercing end of the trocar as it is inserted through the animal's hide. As the implant is pushed through the interior of the trocar to be deposited in the animal, the core of flesh or hide is pushed before the implant into the animal and is deposited with the implant. This prior art method of inserting implants presented the danger of causing infection of the animal by bacteria on the surface of the core of flesh or hide deposited inside the animal with the implant.
To reduce the occurrence of flesh or hide coring in inserting implants into animals, prior art trocars were developed with a solid cutting edge at the piercing tip of the trocar. The solid cutting edge was provided by an insert such as a solid pointed probe that was pushed down through the interior of the needle or trocar to a position where the point of the insert projects just beyond the piercing tip of the trocar. The trocar and the pointed insert received in the trocar were then inserted together through the animal hide and into the animal. Following insertion, the solid insert was withdrawn from the interior of the trocar leaving a pathway through the trocar for the insertion of implants into the animal.
Fine gauge needles having solid points and outlet ports on their sides have also been employed in the delivery of medicament into animals. With these types of needles the medicament is delivered, or a sample is taken, through the side passageway of the needle.
The insertion of implants into animals where the implants have a significantly large diameter has grown in importance as capsulized sustained release substances, such as medicaments or growth agents, have been developed. However, inserting such implants by the prior art method of employing a trocar or large needle have been found to be disadvantaged in that the core of flesh or hide carried into the animal with the insert often leads to infections and abscesses and at times a rejection of the implant. The prior art method of employing a hollow trocar with a solid cutting edge insert pushed through the interior of the trocar has also been found to be disadvantaged in that it is often important that the implant be quickly administered and the quick administration of the implant does not allow time for use of the solid point trocar device. Prior art fine gauge needles typically do not have interior bore dimensions of sufficient size to accommodate capsulized implants.
Prior art devices have been developed in efforts to form an opening through the hide for introducing tubing and other similar apparatus into animals. Typical of these prior art apparatus is the surgical appliance disclosed in U.S. Pat. No. 4,716,901 to Jackson et al. The appliance is generally comprised of a trocar and an expander. The trocar is tubular and is divided into two components by diametrically opposed longitudinally extending cut away openings. Each of the openings taper inwardly from the distal end to the proximal end of the tube and the shape of the openings results in the formation of two trocar components which, at their distal ends, subtend only small angles around the longitudinal axis of the trocar tube. The distal extremities of the two components are adapted to provide a point for piercing the skin in their fully closed condition. The expander comprises a thin tube shorter than the trocar, with an interior bore just large enough to allow a drain tube to slide easily therethrough.
In use of the Jackson et al. appliance, the distal ends of the trocar components pierce the skin and an incision is made by the cutting edges of the components. The end portion of the trocar is then passed through the skin. The expander tube is inserted into the trocar and is passed through the bore of the trocar. The advancing movement of the expander forces the trocar components apart to their fully opened condition, and a drain tube is slid through the expander and the open forward portions of the trocar components. Finally, the trocar and the expander are withdrawn from the incision over the length of the drain tube and the skin stretched by the opening of the trocar contracts on the drain tube gripping it in place.
Although appliances of the type described in the Jackson et al. patent represent advancements over the prior art, they still leave room for improvement when using such devices for the subcutaneous, intermuscular, or interperitoneal injection of implants through animal hide. The incising tip of such devices typically is not specifically designed to produce a single slit incision through the animal hide prior to insertion of the appliance. The trocar components typically are not designed to present as small a cross sectional area as possible of the appliance pushed through the slit incision to facilitate insertion of the components through the incision.